Wires - strikes, cutters and detectors
Wires - strikes, cutters and detectors
Guest
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To: Rotorque
I have often questioned the efficacy of these so-called wire cutters. First of all the cutter mounted on the top of the fuselage is higher in most cases than the tip path of the rotor and would cause contact with the blades before the wire made contact with the cutter. Secondly, if the wire were to make contact with the cutter and be cut the tension on the wire would cause it to whip and be entrained with the spinning blades. Third, if one wire was cut then there may be two to three more wires in the path of the helicopter. Since it takes energy (forward motion of the helicopter) to result in a shearing of the wire then the helicopter will lose some of its’ forward momentum and not be able to cut the remaining wires. The same can be said for the cutter mounted in front of the skids. And finally, what if in the process of cutting the wire contact was made with the adjacent wire by the cut wire or better still, the fuselage of the helicopter? The flash alone would most probably cause the helicopter to explode.
One final thought (OK two final thoughts). Would the flash between the two ends of the separating (cut) wire flash over and weld themselves to the cutter or cause serious damage to the cutter as to render it ineffective to cut the remaining wires if there was sufficient forward momentum? Also, what if the helicopter was flying at an angle relative to the wires? Would this cause the helicopter to skid down the wire and impact the transmission towers?
The best way of avoiding wires is to know where they are and if they are installed looking for the orange balls that are mounted on the high-tension lines. Another more expensive way to avoid wires is to install a LASER RADAR, which was developed by a UK firm several years ago.
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The Cat
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
I have often questioned the efficacy of these so-called wire cutters. First of all the cutter mounted on the top of the fuselage is higher in most cases than the tip path of the rotor and would cause contact with the blades before the wire made contact with the cutter. Secondly, if the wire were to make contact with the cutter and be cut the tension on the wire would cause it to whip and be entrained with the spinning blades. Third, if one wire was cut then there may be two to three more wires in the path of the helicopter. Since it takes energy (forward motion of the helicopter) to result in a shearing of the wire then the helicopter will lose some of its’ forward momentum and not be able to cut the remaining wires. The same can be said for the cutter mounted in front of the skids. And finally, what if in the process of cutting the wire contact was made with the adjacent wire by the cut wire or better still, the fuselage of the helicopter? The flash alone would most probably cause the helicopter to explode.
One final thought (OK two final thoughts). Would the flash between the two ends of the separating (cut) wire flash over and weld themselves to the cutter or cause serious damage to the cutter as to render it ineffective to cut the remaining wires if there was sufficient forward momentum? Also, what if the helicopter was flying at an angle relative to the wires? Would this cause the helicopter to skid down the wire and impact the transmission towers?
The best way of avoiding wires is to know where they are and if they are installed looking for the orange balls that are mounted on the high-tension lines. Another more expensive way to avoid wires is to install a LASER RADAR, which was developed by a UK firm several years ago.
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The Cat
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
[This message has been edited by Lu Zuckerman (edited 09 February 2001).]
Guest
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It is my understanding that the wire strike protection kit is designed to cut wires in cruise flight, i.e. level attitude, cruise speeds. If you encounter said wires on approach to land or climb out after takeoff, the climb/descent angle would permit wire contact with various parts of the blades/fuselage prior to intervention by the cutters. There is also no guarantee that the lower airspeeds during landing/takeoff would permit the cutters to do their job. I agree that the most effective way of dealing with wires is to stay out of them.
Guest
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There wouldn't be many pilots around that deliberatly flew into wires so its a bit redundant to say that they shouldn't. Most ag pilots will tell you to watch out for the wire that you know is there because statistically thats the most dangerous. I personally know a pilot who was saved by the WPS (Wire Strike Protection System)when he accidently flew through a set of wires. Scratch marks made by the departing wire could be seen on the bubble. Very sobering indeed.
Having said all that I'd just like to add, "I'd rather have 'em and not need 'em than need 'em and not have 'em".
Having said all that I'd just like to add, "I'd rather have 'em and not need 'em than need 'em and not have 'em".
Guest
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Wire cutters work ok provided you are in level flight at cruise speed as DPW indicated. They really are only a hopeful last defense to wires possibly being in the area between the rotor and fuse, as you don't want it hitting the main mast.
They are almost to the plane of the rotor, but not higher, or the blades would meet cutter in normal flight. If you are climbing or descending, you likely wouldn't be at the angle for the wires to go into the cutter, they would hit fuse or rotor first, with predictable consequences. If hit at an angle, don't know if it would cut, I would guess that you would as it took tension effect a roll moment to the heli and then the main rotor or tail would intersect the wires, with predictable results.
As it hits the cutter it is guided to the blade which at cruise is more than enough to snap thru it, and as the heli has "Stretched" the wire at that point foreward (if at cruise flight, level attitude, the two ends are pulled away from the 'copter as it continues to move forward, there is at that point of cut, the tension causes those ends to spring away from the heli.
Which the amount of tension at that point it can move the ends get away fairly fast. Likely fast enough that any arc between wouldn't bond them to the cutter. (One should see the results of an arresting cable break, not something I want to repeat twice in my lifetime I assure you.
Realistically it is best to avoid wires altogether. If you see some, FIND the tower and fly over it. Never, if you can avoid it go between towers, as you may not see the wires until the last possible moment.
Had 1 UH-1N suffer a multiple wire strike, the cutter clipped both, there was enough room between them. The cutter had markings consistant with an arc, but I think that when you first hit a wire, you have an arc that now makes the heli equal to the energy level of the wire (power co. Heli's bond themselves tot eh wire before the worker goes to work on them), But if it is at the moment of cutting, I believe the ends move away too fast to be welded to the cutter at that point. If it happened however, I would think it would be a weak point on that wire now being tensioned by the forward speed of the heli and the cutter would still part it (if it were the second? Don't know, ours did a second, but three? Boy I think one could see three wires coming.)
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Marc
They are almost to the plane of the rotor, but not higher, or the blades would meet cutter in normal flight. If you are climbing or descending, you likely wouldn't be at the angle for the wires to go into the cutter, they would hit fuse or rotor first, with predictable consequences. If hit at an angle, don't know if it would cut, I would guess that you would as it took tension effect a roll moment to the heli and then the main rotor or tail would intersect the wires, with predictable results.
As it hits the cutter it is guided to the blade which at cruise is more than enough to snap thru it, and as the heli has "Stretched" the wire at that point foreward (if at cruise flight, level attitude, the two ends are pulled away from the 'copter as it continues to move forward, there is at that point of cut, the tension causes those ends to spring away from the heli.
Which the amount of tension at that point it can move the ends get away fairly fast. Likely fast enough that any arc between wouldn't bond them to the cutter. (One should see the results of an arresting cable break, not something I want to repeat twice in my lifetime I assure you.
Realistically it is best to avoid wires altogether. If you see some, FIND the tower and fly over it. Never, if you can avoid it go between towers, as you may not see the wires until the last possible moment.
Had 1 UH-1N suffer a multiple wire strike, the cutter clipped both, there was enough room between them. The cutter had markings consistant with an arc, but I think that when you first hit a wire, you have an arc that now makes the heli equal to the energy level of the wire (power co. Heli's bond themselves tot eh wire before the worker goes to work on them), But if it is at the moment of cutting, I believe the ends move away too fast to be welded to the cutter at that point. If it happened however, I would think it would be a weak point on that wire now being tensioned by the forward speed of the heli and the cutter would still part it (if it were the second? Don't know, ours did a second, but three? Boy I think one could see three wires coming.)
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Marc
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Following a Australian Army 206 many years ago when it hit a wire. Classic case, one pole on the side of the road, 2nd pole 60m away in trees. Anyway, wire went through the small gap between the disc and the top cutter, and snapped the pitch change rods. 1 dead, 2 vsi. They don't always work.
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Regarding the Laser Radar wire detector that Lu mentioned, the only one I've heard about weighed ~600lbs and could only detect approximately horizontal wires with little clutter around them, but not all the time (I forget the percentage..it wasn't 100%).
The idea seemed sound to me, but since I'm planning on avoiding the wires, I fly where the trees are tall (so they clutter the wires), there are many wires that are not horizontal (ie large spans or skyline logging cables), and I have other ways of using that 600 lbs, I didn't think the wire detector would be that useful.
Also, there was a question whether the detector would pick up a wire threat with enough time for you to do something about it.
Does this one developed in the UK have similiar limitations?
[This message has been edited by heedm (edited 10 February 2001).]
The idea seemed sound to me, but since I'm planning on avoiding the wires, I fly where the trees are tall (so they clutter the wires), there are many wires that are not horizontal (ie large spans or skyline logging cables), and I have other ways of using that 600 lbs, I didn't think the wire detector would be that useful.
Also, there was a question whether the detector would pick up a wire threat with enough time for you to do something about it.
Does this one developed in the UK have similiar limitations?
[This message has been edited by heedm (edited 10 February 2001).]
Guest
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Lu, They do work if used. One above said they dont work, but the accident mentioned the wires went above it. I have seen the UH-1 after taking out some small Military wires low level. Marks on the cutters and nothing else other than some Field Commander bitching about his loss of Commo. I dont really think they were designed for high tension wires, but if a Huey blade will cut one Im sure the wires cutters will give it a good go.
As you said best prevention is to pretend you dont have them and stay the hell away from wires.
I have lost many friends to this type of accident.
As you said best prevention is to pretend you dont have them and stay the hell away from wires.
I have lost many friends to this type of accident.
Guest
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To all
I have spent three years patroling wires, mainly 11Kv (single wooden pole) and I have a healthy respect for them.
Occasionaly these wires ran underneath major grid wires and nessesitated the need to fly (hover taxi) under them, it was not always possible to cross near the pylons, which would have given you somthing to focus on however if you draw an imaginary line on the ground joining up both pylons that support the section that you intend to pass under I found that gave better situational awareness than trying to judge the distance to the wire itself.
My heart sinks evertime I hear that some poor sod has become wrapped up in wires. Whilst most of these can be easily avoided by good airmanship there are those that can catch out the very best of us, and in this age of information technology it is not beyond imagination that a system can be devised to protect the unwary. I have had some thought on the matter and would like to here the response on the following from all cancearned.
Most if not all poles (wooden to pylon) have an identity number and if the GPS position and height AMSL is known then a database could be compiled and software writen for integration with existing GPS to warn the pilot when in the vacinity and height of known wires. It would also be possible to display the info similar to TCAS as your track, velocity and height are known (GPS), even resolution advisories given to facilitate timely avoidance.
I apreciate the fact that only known wires would trigger a alarm but here in the UK we don't have many logging wires strung across valley's,
well none that Ive seen!!!!.
Maybe a system combining the RADAR, EMF sensing and GPS datadased detection would provide a second line of defense that maybe saves lives.
I have spent three years patroling wires, mainly 11Kv (single wooden pole) and I have a healthy respect for them.
Occasionaly these wires ran underneath major grid wires and nessesitated the need to fly (hover taxi) under them, it was not always possible to cross near the pylons, which would have given you somthing to focus on however if you draw an imaginary line on the ground joining up both pylons that support the section that you intend to pass under I found that gave better situational awareness than trying to judge the distance to the wire itself.
My heart sinks evertime I hear that some poor sod has become wrapped up in wires. Whilst most of these can be easily avoided by good airmanship there are those that can catch out the very best of us, and in this age of information technology it is not beyond imagination that a system can be devised to protect the unwary. I have had some thought on the matter and would like to here the response on the following from all cancearned.
Most if not all poles (wooden to pylon) have an identity number and if the GPS position and height AMSL is known then a database could be compiled and software writen for integration with existing GPS to warn the pilot when in the vacinity and height of known wires. It would also be possible to display the info similar to TCAS as your track, velocity and height are known (GPS), even resolution advisories given to facilitate timely avoidance.
I apreciate the fact that only known wires would trigger a alarm but here in the UK we don't have many logging wires strung across valley's,
well none that Ive seen!!!!.
Maybe a system combining the RADAR, EMF sensing and GPS datadased detection would provide a second line of defense that maybe saves lives.
Guest
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Wire detection
To all
I have spent a few years patrolling wires; mainly 11Kv (single wooden pole) and I have a healthy respect for them.
Occasionally these wires ran underneath major grid wires and necessitated the need to fly (hover taxi) under them, it was not always possible to cross near the pylons, which would have given you something to focus on however I found that if you draw an imaginary line on the ground joining up both pylons that support the section that you intend to pass under this gives better situational awareness than trying to judge the distance to the wire itself, however this only works well when the pylon run is easily defined and is not much help when operating around power stations where ultimately all patrols end up
My heart sinks every time I hear that some poor sod has become wrapped up in wires. Whilst most of these can be easily avoided by good airmanship, but there are those that can catch out the very best of us, and in this age of information technology it is not beyond imagination that a system can be devised to protect the unwary or the unlucky. I have had some thought on the matter and would like to here the response on the following from all concerned.
Most if not all poles (wooden to pylon) have an identity number. If the GPS position and height AMSL is known then a database could be compiled and software written to integrate with existing GPS types to warn the pilot when in the vicinity (and height banding) of known wires. It would also be possible to display the info in a similar format to TCAS as your track; velocity and height are known (GPS). Maybe even resolution advisories given to facilitate timely avoidance.
I appreciate the fact that only known wires would trigger an alarm but here in the UK we don't have many logging wires strung across valleys,
well none that I’ve seen!!!!.
Maybe a system combining the RADAR, EMF sensing, IR and GPS database detection would provide a second line of defense that maybe saves lives.
I have spent a few years patrolling wires; mainly 11Kv (single wooden pole) and I have a healthy respect for them.
Occasionally these wires ran underneath major grid wires and necessitated the need to fly (hover taxi) under them, it was not always possible to cross near the pylons, which would have given you something to focus on however I found that if you draw an imaginary line on the ground joining up both pylons that support the section that you intend to pass under this gives better situational awareness than trying to judge the distance to the wire itself, however this only works well when the pylon run is easily defined and is not much help when operating around power stations where ultimately all patrols end up
My heart sinks every time I hear that some poor sod has become wrapped up in wires. Whilst most of these can be easily avoided by good airmanship, but there are those that can catch out the very best of us, and in this age of information technology it is not beyond imagination that a system can be devised to protect the unwary or the unlucky. I have had some thought on the matter and would like to here the response on the following from all concerned.
Most if not all poles (wooden to pylon) have an identity number. If the GPS position and height AMSL is known then a database could be compiled and software written to integrate with existing GPS types to warn the pilot when in the vicinity (and height banding) of known wires. It would also be possible to display the info in a similar format to TCAS as your track; velocity and height are known (GPS). Maybe even resolution advisories given to facilitate timely avoidance.
I appreciate the fact that only known wires would trigger an alarm but here in the UK we don't have many logging wires strung across valleys,
well none that I’ve seen!!!!.
Maybe a system combining the RADAR, EMF sensing, IR and GPS database detection would provide a second line of defense that maybe saves lives.
Guest
Posts: n/a
A VERY good idea and more relevant now GPS is more accurate (the de-rating of accuracy now removed by US military).
If all wires, posts and pylons were surveyed over a period (maybe during maintenance) then a database (silimar to Jeppeson, or even part of it) could be built up and loaded to any GPS. Even the wires themselves could be shown on the moving map.
Big job? Not as big as putting them all there in the first place and that got done...
All new installations could be entered as they are built as matter of obligation, all exisiting could be surveyed by the firms patrolling, Pilots from every district could send in info. to be ratified by a central mapping agency. All anyone needs to supply their local wire/post info is a GPS and a pen......! Info could even be downloaded to a central computer over the net...All the technology is there right now.
Care would have to be taken that pilots do not become too dependant on such a system and fly into unlisted wires as a result but that would only require the same amount of caution that ALL GPS derived information should be treated with. An EMF proximity warning system could help in that direction too.
I've always thought that EMF would be (should be) easy to detect, one may do it at home (in a crude way) using a $10 microphone connected to any amplifier.
The two systems used in conjunction could be a very important step forward. Wires are a major problem here in NZ (as they are in other Countries). I am going to forward this excellent idea on to NZ CAA right now.
Well done.
If all wires, posts and pylons were surveyed over a period (maybe during maintenance) then a database (silimar to Jeppeson, or even part of it) could be built up and loaded to any GPS. Even the wires themselves could be shown on the moving map.
Big job? Not as big as putting them all there in the first place and that got done...
All new installations could be entered as they are built as matter of obligation, all exisiting could be surveyed by the firms patrolling, Pilots from every district could send in info. to be ratified by a central mapping agency. All anyone needs to supply their local wire/post info is a GPS and a pen......! Info could even be downloaded to a central computer over the net...All the technology is there right now.
Care would have to be taken that pilots do not become too dependant on such a system and fly into unlisted wires as a result but that would only require the same amount of caution that ALL GPS derived information should be treated with. An EMF proximity warning system could help in that direction too.
I've always thought that EMF would be (should be) easy to detect, one may do it at home (in a crude way) using a $10 microphone connected to any amplifier.
The two systems used in conjunction could be a very important step forward. Wires are a major problem here in NZ (as they are in other Countries). I am going to forward this excellent idea on to NZ CAA right now.
Well done.
Guest
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I flew powerline patrol for about eleven years and the power company had a map coordinate for most every distribution, and transmission pole and structrue, also for , pole mounted and pad mounted transformers, switches, relays etc. GPS locating is perhaps possible. The pole location is known, but I am not sure if the map coordianates are usable as they are not lat/long, most were grid locations from USGS survey maps.
The software memory to plot pole locations for one powerline could be daunting, one line could have a thousand poles on it. Isn't the military working on millimeter radar for this purpose?
Keep in mind if you are just flying over powerlines not look for the lines, look for the pole or structure, they are much easier to see than the line itself! Also, the pole or structure is the highest point on the line so cross over the pole and you will be safe.
Has anyone heard of wire strike kits that will cut the high voltage lines, say 130KV and above? Or the steel reinforced aluminum lines?
The software memory to plot pole locations for one powerline could be daunting, one line could have a thousand poles on it. Isn't the military working on millimeter radar for this purpose?
Keep in mind if you are just flying over powerlines not look for the lines, look for the pole or structure, they are much easier to see than the line itself! Also, the pole or structure is the highest point on the line so cross over the pole and you will be safe.
Has anyone heard of wire strike kits that will cut the high voltage lines, say 130KV and above? Or the steel reinforced aluminum lines?
Guest
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This sounds like a good idea, however in many areas of the UK, for example, there are so many powerlines that pilots would probably suffer an information overload. The warning would possibly be going off so often that it would become counterproductive. We all know what happens then. The pilot turns off the equipment.
I was involved in an RAF trial around 1980 in the Puma, using a device that showed the nearest wires using a magnetic field detection system. The information was portrayed on a small dial presenting the direction of the wires. Where there were many wires it became impossible to decipher where the real threat was.
The device did not enter production to my knowledge.
With any device using a database, keeping it updated is a big problem.
I'm sure it's possible to overcome the problems but as usual it's financial considerations that take priority.
I was involved in an RAF trial around 1980 in the Puma, using a device that showed the nearest wires using a magnetic field detection system. The information was portrayed on a small dial presenting the direction of the wires. Where there were many wires it became impossible to decipher where the real threat was.
The device did not enter production to my knowledge.
With any device using a database, keeping it updated is a big problem.
I'm sure it's possible to overcome the problems but as usual it's financial considerations that take priority.
Guest
Posts: n/a
Absolutely it can be a problem in areas where their are a lot of wires, the screen could end up resembling scribble!
I wonder if it would be good to only display the next three lines in your current path?
Agree that the database needs be kept right up to date. Presumably any agency that wants to put up a pole or pylon forming any part of a line would have to seek permission to do so and could database entry/maintenance be made a condition of all and any permission(s) granted?
I wonder if it would be good to only display the next three lines in your current path?
Agree that the database needs be kept right up to date. Presumably any agency that wants to put up a pole or pylon forming any part of a line would have to seek permission to do so and could database entry/maintenance be made a condition of all and any permission(s) granted?
Guest
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Thanks for the response
SPS
Let me know what kind or response you get.
EMI detection will only work when the line is live, I/R I’m sure is the same but I will take advice on that, if so these have shortfalls in so much as they will not detect Earth, telephone, or Guy lines etc.
As you know the power lines run generally in a straight line and therefore it would only be necessary to plot the first and last in any straight run this would reduce the amount of memory required. I envisage a protected area of 600m (300m either side of the line) the benefit of this is two fold, 1. Gives you time to take avoiding action 2. This would allow for slight doglegs in the runs (reducing the amount of memory needed).
As modern GPS’s are now reliable and the signal and accuracy constantly monitored (RAIM) spurious warnings can be reduced or eliminated, the type of warning given would be dependant on the flight path and velocity of the A/C it would also be possible to make to protected zone around the lines vary in width according to the closing speed of the A/C i.e. 100kts closing would trigger a resolution at 1000 m, 50 kts 600m and so on. This would need the input from a radalt to stop warnings when over flying
Good point about who would pay.
I wonder how much lost revenue, let alone the repair cost the power companies suffer every ten years to this kind of incident? Would they pay towards such a system?
Insurance companies could offer lower premiums to police and medical helicopter operators?
SPS
Let me know what kind or response you get.
EMI detection will only work when the line is live, I/R I’m sure is the same but I will take advice on that, if so these have shortfalls in so much as they will not detect Earth, telephone, or Guy lines etc.
As you know the power lines run generally in a straight line and therefore it would only be necessary to plot the first and last in any straight run this would reduce the amount of memory required. I envisage a protected area of 600m (300m either side of the line) the benefit of this is two fold, 1. Gives you time to take avoiding action 2. This would allow for slight doglegs in the runs (reducing the amount of memory needed).
As modern GPS’s are now reliable and the signal and accuracy constantly monitored (RAIM) spurious warnings can be reduced or eliminated, the type of warning given would be dependant on the flight path and velocity of the A/C it would also be possible to make to protected zone around the lines vary in width according to the closing speed of the A/C i.e. 100kts closing would trigger a resolution at 1000 m, 50 kts 600m and so on. This would need the input from a radalt to stop warnings when over flying
Good point about who would pay.
I wonder how much lost revenue, let alone the repair cost the power companies suffer every ten years to this kind of incident? Would they pay towards such a system?
Insurance companies could offer lower premiums to police and medical helicopter operators?
Guest
Posts: n/a
I'll let you know of any response by private post to preserve......well, things...!
In NZ the power companies have agreed to bear the cost of providing and fitting those orange balls on risky lines which is great but identifiaction of which ones are a danger seems to be causing problems. It won't happen overnight and it won't be all lines.
I still prefer the GPS database and detection idea, although the balls work for those who are not so equipped.
So let's have ALL of them...
In NZ the power companies have agreed to bear the cost of providing and fitting those orange balls on risky lines which is great but identifiaction of which ones are a danger seems to be causing problems. It won't happen overnight and it won't be all lines.
I still prefer the GPS database and detection idea, although the balls work for those who are not so equipped.
So let's have ALL of them...
Guest
Posts: n/a
Heard a rumour here at Heli Expo today that Erickson are looking at getting a Wire strike kit made for the S-64. Now that will be a heck of a system. Aparently they had a strike not that long ago and shook them into looking at some sort of protection.
With their machines predominantly out working on fires in foreign countries the protection might be worth adding to the machines, but I suppose it also depends on the cost since they only have 19 of the Skycranes.
With their machines predominantly out working on fires in foreign countries the protection might be worth adding to the machines, but I suppose it also depends on the cost since they only have 19 of the Skycranes.
Guest
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The last time I talked to anybody at Bristol (inventor of the WSPS) they claimed several hundred "saves". As earlier posters pointed out, it doesn't work every time, but it works often enough to make it a worthwile investment, in my opinion. Bristol is very careful about statements about what wire sizes can be cut, but I have seen multistrand steel structural cables over .5 inch in diameter cut. By the way, the cable is usually not cut clean through. The WSPS notches the cable, and the continuing forward motion of the helicopter yanks on the wire, causing a tension failure at the notch.